Robust planar composite with an intermediate layer of increased vicat softening temperature

ABSTRACT

The present invention generally relates to a sheetlike composite ( 3 ) comprising a layer configuration with the following layers: 0. optionally a layer of thermoplastic KSu ( 13 ); 1. a carrier layer ( 4 ); ii. a first layer of thermoplastic KSv ( 35 ); iii. a barrier layer ( 5 ); iv. a second layer of thermoplastic KSa ( 6 ); v. at least one further layer of thermoplastic KSw ( 7 ); wherein the Vicat softening temperature of the layer of thermoplastic KSv ( 35 ) and the Vicat softening temperature of the layer of thermoplastic KSa ( 6 ) is in each case higher than the Vicat softening temperature of the layer of thermoplastic KSw ( 7 ). The present invention furthermore relates to a process for the production of the sheetlike composite, a container which surrounds an interior and comprises at least one such sheetlike composite, and a process for the production of this container.

The present invention generally relates to a sheetlike compositecomprising a layer configuration with the following layers:

-   -   o. optionally a layer of thermoplastic KSu;    -   i. a carrier layer;    -   ii. a first layer of thermoplastic KSv;    -   iii. a barrier layer;    -   iv. a second layer of thermoplastic KSa;    -   v. a third layer of thermoplastic KSw,

The present invention further relates to a process for the production ofthe sheetlike composite, a container which surrounds an interior andcomprises at least one such sheetlike composite, and a process for theproduction of this container.

For a long time foodstuffs, whether foodstuffs for human consumption oralso animal feed products, have been preserved by being stored either ina can or in a glass jar closed with a lid. However, these packagingsystems have some serious disadvantages, inter alia the high intrinsicweight, the energy-intensive production and the troublesome opening.

Alternative packaging systems for storing foodstuffs for a long periodof time as far as possible without impairment are known from the priorart. These are containers produced from sheetlike composites—often alsocalled laminate. Such sheetlike composites are often built up from alayer of thermoplastic, a carrier layer usually made of cardboard orpaper, an adhesion promoter layer, an aluminium layer and a furtherlayer of plastic. Such a sheetlike composite is disclosed, inter alia,in WO 90/09926. Such laminated containers already have many advantagesover the conventional glass jars and cans, for example space-savingstorage and low intrinsic weight. Nevertheless, possibilities forimprovement also exist for these packaging systems.

In regions of the sheetlike composites which are exposed to highmechanical stresses during production of the container, in particular ifbarrier layers of aluminium foil are employed, the formation of smalldefects, such as cracks, fractures, blisters or non-sealed pockets ormicrochannels up to leaks, thus occurs again and again. Germs can bedeposited in such defects, or even penetrate into the containers, as aresult of which the foodstuff in the container may decay more easily.Any damage to the barrier layer furthermore leads to trouble spots inrespect of entry of oxygen into the container, which in turn leads tolosses in the quality of the foodstuff and also to a shortened shelflife. Regions which contain scores or folded edges or weaknesses in thesheetlike composite are particularly at risk, especially those regionswhich have scored crosses and are folded particular severely or inseveral dimensions during production of the container.

Generally, the object of present invention is to at least partlyeliminate the disadvantages emerging from the prior art.

There is furthermore the object of providing a sheetlike composite whichis distinguished by an improved impermeability to vapour and oxygencoupled with easy processability and high reliability, in particularwithout the formation of defects.

A further object is to provide a composite which has a sealing windowwhich is as large as possible.

A further object is to provide a sheetlike composite which is suitablein particular for the production of containers for transportation andstorage of milk, milk products, drinks containing vitamin C and otherdrinks, foodstuffs, drinks of low carbonic acid content or animal feedproducts and the like.

A contribution towards achieving at least one of the abovementionedobjects is made by the subject matter of the category building claims.The subject matter of the sub-claims which are dependent upon thecategory building claims represents preferred embodiments of thiscontribution towards achieving the objects.

A contribution towards achieving at least one of the above objects ismade by a sheetlike composite comprising a layer configuration with thefollowing layers, preferably in the sequence shown:

-   -   o. optionally or necessarily a layer of thermoplastic KSu;    -   i. a carrier layer;    -   ii. a first layer of thermoplastic KSv;    -   iii. a barrier layer;    -   iv. a second layer of thermoplastic KSa;    -   v. a third layer of thermoplastic KSw;    -   wherein the Vicat softening temperature of the layer of        thermoplastic KSv and the Vicat softening temperature of the        layer of thermoplastic KSa is in each case higher than the Vicat        softening temperature of the layer of thermoplastic KSw.

The term “joined” used in this description includes the adhesion of twoobjects beyond van der Waals forces of attraction. These objects caneither follow one another directly or be joined to one another viafurther objects. For the sheetlike composite, this means, for example,that the carrier layer can be joined directly and therefore immediatelyto the layer of thermoplastic KSv, or also indirectly via an adhesionpromoter layer, a direct joining being preferred.

The wording “comprising a layer configuration with layers, preferably inthe sequence shown” as used above means that at least the stated layersare present in the composite according to the invention in the sequenceshown. This wording does not necessarily mean that these layers followone another directly. Rather, this wording includes constellations inwhich one or more additional layers can moreover be present between twolayers mentioned successively in the above sequence. In addition to theabovementioned layer configuration, one or more further layers canlikewise be present as a part of the composite. Thus, for example, atleast one further layer of thermoplastic KSu can be provided on the sideof the carrier layer directed towards the environment. The layer ofthermoplastic KSu can also be joined here indirectly or directly to thecarrier layer, direct joining being preferred. Furthermore, for example,a further layer or several further layers may additionally be providedover the complete or a part of the area on the side of the layer ofthermoplastic KSu facing the environment. In particular, a printed layermay also be applied on the side of the layer of thermoplastic KSu facingthe environment. However, possible further layers are also covering orprotective layers. According to another embodiment, it is also possiblefor a printed layer to be provided between the carrier layer and thelayer of thermoplastic KSu. In this case, the layer of thermoplastic KSuitself could also be a covering or protective layer for the printedlayer.

If the sheetlike composite comprises at least one further layer ofthermoplastic KSu, this conventionally has a weight per unit area in arange of from 5 to 50 g/m², particularly preferably in a range of from 8to 40 g/m² and most preferably in a range of from 10 to 30 g/m².Preferably, the layer of thermoplastic KSu comprises a thermoplasticpolymer to the extent of at least 70 wt. %, preferably at least 80 wt. %and particularly preferably at least 95 wt. %, in each case based on thelayer of thermoplastic KSu. Possible suitable thermoplastics of thelayer of thermoplastic KSu are in particular those which can be easilyprocessed due to good extrusion properties. Among these, polymersobtained by chain polymerization are suitable, in particular polyestersor polyolefins, cyclic olefin copolymers (COC), polycyclic olefincopolymers (POC), in particular polyethylene and polypropylene, beingparticularly preferred and polyethylene being very particularlypreferred. Mixtures of at least two thermoplastics can also be employedfor the layer of thermoplastic KSu.

Among the polyethylenes, HDPE, MDPE, LDPE, LLDPE, VLDPE and PE andmixtures of at least two of these are preferred according to the presentinvention. Suitable polyethylenes have a melt flow rate (MFR) in a rangeof from 1 to 25 g/10 min, preferably in a range of from 2 to 20 g/10 minand particularly preferably in a range of from 2.5 to 15 g/10 min, and adensity in a range of from 0.890 g/cm³ to 0.980 g/cm³, preferably in arange of from 0.895 g/cm³ to 0.975 g/cm³, and further preferably in arange of from 0.900 g/cm³ to 0.970 g/cm³. The at least one thermoplasticpolymer contained in the layer of thermoplastic KSu, preferably all thepolymers contained in the layer of thermoplastic KSu, preferably has amelting temperature in a range of from 80 to 155° C., preferably in arange of from 90 to 145° C. and particularly preferably in a range offrom 95 to 135° C.

As the carrier layer, any material which is suitable for this purpose tothe person skilled in the art and which has an adequate strength andrigidity to give the container stability to the extent that in thefilled state the container essentially retains its shape can beemployed. In addition to a number of plastics, plant-based fibroussubstances, in particular pulps, preferably sized, bleached and/ornon-bleached pulps are preferred, paper and cardboard being particularlypreferred. The weight per unit area of the carrier layer is preferablyin a range of from 120 to 450 g/m², particularly preferably in a rangeof from 130 to 400 g/m² and most preferably in a range of from 140 to380 g/m². A suitable cardboard as a rule has a single- or multilayerconfiguration and can be coated on one or both sides with one or alsomore covering layers. A suitable cardboard furthermore has a residualmoisture content of less than 20 wt. %, preferably from 2 to 15 wt. %and particularly preferably from 4 to 10 wt. %.

The plastics which have already been described above for the layer ofthermoplastic KSu can preferably be employed, in particular, as thelayer of thermoplastic KSv which preferably has a weight per unit areain a range of from 5 to 40 g/m², particularly preferably from 8 to 30g/m² and moreover preferably from 10 to 25 g/m². Furthermore, the Vicatsoftening temperature of the layer of thermoplastic KSv is in a range offrom 90° C. to 150° C., preferably from 95° C. to 140° C. andparticularly preferably from 100° C. to 135° C.

In a preferred embodiment example, the layer of thermoplastic KSv ispresent as a mixture of at least two thermoplastics. In this connection,it is furthermore preferable for the layer of plastic KSv to comprise atleast 25 wt. %, particularly preferably at least 35 wt. % and mostpreferably at least 45 wt. %, in each case based on the layer of plasticKSv, of a thermoplastic which has a Vicat softening temperature of atleast 90° C., preferably at least 95° C. and particularly preferably atleast 100° C. This thermoplastic furthermore preferably has a meltingpoint of at least 110° C., preferably at least 115° C. and particularlypreferably at least 120° C. This thermoplastic moreover preferably has adensity of at least 0.918 g/cm³, preferably at least 0.922 g/cm³,particularly preferably at least 0.925 g/cm³ and moreover preferably atleast 0.930 g/cm³.

In a particular embodiment of the abovementioned embodiment example, thelayer of plastic KSv is present as a mixture of a polyolefin prepared bymeans of a metallocene catalyst and a further polymer, the furtherpolymer preferably being a polyolefin which has not been prepared bymeans of a metallocene catalyst, preferably a polyethylene which has notbeen prepared by means of a metallocene catalyst (mPE). Particularlypreferably, the layer of thermoplastic KSv is present as a mixture of 25to 95 wt. %, preferably 35 to 85 wt. % and particularly preferably 45 to75 wt. % of mPE and 5 to 75 wt. %, preferably 15 to 65 wt. % andparticularly preferably 25 to 55 wt. % of PE, the mPE described herefulfilling at least one, preferably at least two and particularlypreferably all of the parameters of Vicat softening temperature, meltingtemperature, MFR value and density mentioned above for the layer ofthermoplastic KSv.

As the barrier layer, any material which is suitable for this purpose tothe person skilled in the art and has an adequate barrier action, inparticular against oxygen, can be employed. The barrier layer ispreferably chosen from

-   -   a. a barrier layer of plastic;    -   b. a metal layer;    -   c. a metal oxide layer; or    -   d. a combination of at least two of a. to c.

If the barrier layer is a barrier layer of plastic according toalternative a., this preferably comprises at least 70 wt. %,particularly preferably at least 80 wt. % and most preferably at least95 wt. % of at least one plastic which is known to the person skilled inthe art for this purpose, in particular because of aroma or gas barrierproperties which are suitable for packaging containers. Possibleplastics, in particular thermoplastics, here are plastics carrying N orO, both by themselves and in mixtures of two or more. According to theinvention, it may prove advantageous if the barrier layer of plastic hasa melting temperature in a range of from more than 155 to 300° C.,preferably in a range of from 160 to 280° C. and particularly preferablyin a range of from 170 to 270° C.

Further preferably, the barrier layer of plastic has a weight per unitarea in a range of from 2 to 120 g/m², preferably in a range of from 3to 60 g/m², particularly preferably in a range of from 4 to 40 g/m² andmoreover preferably from 6 to 30 g/m². Furthermore preferably, thebarrier layer of plastic is obtainable from melts, for example byextrusion, in particular layer extrusion. Moreover preferably, thebarrier layer of plastic can also be introduced into the sheetlikecomposite via lamination. It is preferable here for a film to beincorporated into the sheetlike composite. According to anotherembodiment, barrier layers of plastic which are obtainable by depositionfrom a solution or dispersion of plastics can also be chosen.

Possible suitable polymers are preferably those which have aweight-average molecular weight, determined by gel permeationchromatography (GPC) by means of light scattering, in a range of from3×10³ to 1×10⁷ g/mol, preferably in a range of from 5×10³ to 1×10⁶ g/moland particularly preferably in a range of from 6×10³ to 1×10⁵ g/mol.Possible suitable polymers are, in particular, polyamide (PA) orpolyethylene/vinyl alcohol (EVOH) or a mixture thereof.

Among the polyamides, all PAs which seem suitable for the use accordingto the invention to the person skilled in the art are possible. PA 6, PA6.6, PA 6.10, PA 6.12, PA 11 or PA 12 or a mixture of at least two ofthese are to be mentioned in particular, PA 6 and PA 6.6 beingparticularly preferred and PA 6 furthermore being preferred. PA 6 iscommercially obtainable, for example, under the trade names Akulon®,Durethan® and Ultramid®. Amorphous polyamides, such as e.g. MXD6,Grivory® and Selar® PA, are moreover suitable. It is further preferablefor the PA to have a density in a range of from 1.01 to 1.40 g/cm³,preferably in a range of from 1.05 to 1.30 g/cm³ and particularlypreferably in a range of from 1.08 to 1.25 g/cm³. Furthermore, it ispreferable for the PA to have a viscosity number in a range of from 130to 185 ml/g and preferably in a range of from 140 to 180 ml/g.

As EVOH, all EVOHs which seem suitable for the use according to theinvention to the person skilled in the art are possible. Examples ofthese are, inter alia, commercially obtainable in a large number ofdifferent configurations under the trade name EVAL™ from EVAL Europe NV,Belgium, for example the types EVAL™ F104B or EVAL™ LR171B. PreferredEVOHs have at least one, two, several or all of the followingproperties:

-   -   an ethylene content in a range of from 20 to 60 mol %,        preferably from 25 to 45 mol %;    -   a density in a range of from 1.0 to 1.4 g/cm³, preferably from        1.1 to 1.3 g/cm³;    -   a melting point in a range of from more than 155 to 235° C.,        preferably from 165 to 225° C.;    -   an MFR value (210° C./2.16 kg if T_(M(EVOH))<230° C.; 230°        C./2.16 kg if 210° C.<T_(M(EVOH))<230° C.) in a range of from 1        to 25 g/10 min, preferably from 2 to 20 g/10 min;    -   an oxygen permeation rate in a range of from 0.05 to 3.2 cm³·20        μm/m²·day·atm, preferably in a range of from 0.1 to 1 cm³·20        μm/m²·day·atm.

According to alternative b. the barrier layer is a metal layer. Alllayers with metals which are known to the person skilled in the art andcan provide a high impermeability to light and oxygen are suitable inprinciple as the metal layer. According to a preferred embodiment, themetal layer can be present as a foil or as a deposited layer, e.g.formed by a physical gas phase deposition. The metal layer is preferablyan uninterrupted layer. According to a further preferred embodiment, themetal layer has a thickness in a range of from 3 to 20 μm, preferably arange of from 3.5 to 12 μm and particularly preferably in a range offrom 4 to 10 μm.

Metals which are preferably chosen are aluminium, iron or copper. Asteel layer, e.g. in the form of a foil, may be preferred as an ironlayer. Furthermore preferably, the metal layer is a layer withaluminium. The aluminium layer can expediently be made of an aluminiumalloy, such as, for example, AlFeMn, AlFe1.5Mn, AlFeSi or AlFeSiMn. Thepurity is conventionally 97.5% and higher, preferably 98.5% and higher,in each case based on the total aluminium layer. In a particularembodiment, the metal layer is made of an aluminium foil. Suitablealuminium foils have an extensibility of more than 1%, preferably ofmore than 1.3% and particularly preferably of more than 1.5%, and atensile strength of more than 30 N/mm², preferably more than 40 N/mm²and particularly preferably more than 50 N/mm². Suitable alloys forestablishing aluminium layers or foils are commercially obtainable underthe designations EN AW 1200, EN AW 8079 or EN AW 8111 from HydroAluminium Deutschland GmbH or Amcor Flexibles Singen GmbH.

In the case of a metal foil as the barrier layer, an adhesion promotercan be provided between the metal foil and the next layer ofthermoplastic on one and/or both sides of the metal foil. According to aparticular embodiment of the container according to the invention,however, an adhesion promoter is provided between the metal foil and thenext layer of thermoplastic on no side of the metal foil.

Furthermore preferably, a metal oxide layer can be chosen as the barrierlayer according to alternative c. Possible metal oxide layers are allmetal oxide layers which are familiar and seem suitable to the personskilled in the art for achieving a barrier action against light, vapourand/or gas. Metal oxide layers based on the metals aluminium, iron orcopper already mentioned above and those metal oxide layers based ontitanium or silicon oxide compounds are preferred in particular. A metaloxide layer is produced, by way of example, by vapour deposition of ametal oxide on a layer of plastic, for example an orientatedpolypropylene film. A preferred process for this is physical gas phasedeposition.

According to a further preferred embodiment, the metal layer or themetal oxide layer can be present as a layer composite of one or morelayers of plastic with a metal layer. Such a layer is obtainable, forexample, by vapour deposition of a metal on a layer of plastic, forexample an orientated polypropylene film. A preferred process for thisis physical gas phase deposition.

According to a further preferred embodiment of the composite accordingto the invention, the sheetlike composite according to the inventioncontains at least the layers of thermoplastic KSv, KSa and KSw, wherethe layer of thermoplastic KSa follows the barrier layer, and preferablyfollows indirectly. The layer of thermoplastic KSw preferably followsthe layer of plastic KSa, and particularly preferably follows directly.

The layer of thermoplastic KSa preferably has a weight per unit area ina range of from 5 to 50 g/m², particularly preferably from 8 to 40 g/m²and moreover preferably from 10 to 30 g/m². The plastics which havealready been described above for the layer of thermoplastic KSu, inparticular, can in turn preferably be employed. Furthermore, the Vicatsoftening temperature of the layer of thermoplastic KSa is in a range offrom 90° C. to 150° C., preferably from 95° C. to 140° C. andparticularly preferably from 100° C. to 135° C.

In a preferred embodiment example, the layer of thermoplastic KSa ispresent as a mixture of at least two thermoplastics. In this connection,it is furthermore preferable for the layer of thermoplastic KSa tocomprise at least 25 wt. %, particularly preferably at least 35 wt. %and most preferably at least 45 wt. %, in each case based on the layerof thermoplastic KSa, of a thermoplastic which has a Vicat softeningtemperature of at least 90° C., preferably at least 95° C. andparticularly preferably at least 100° C. This thermoplastic furthermorepreferably has a melting point of at least 110° C., preferably at least115° C. and particularly preferably at least 120° C. This thermoplasticmoreover preferably has a density of at least 0.918 g/cm³, preferably atleast 0.922 g/cm³, particularly preferably at least 0.925 g/cm³ andmoreover preferably at least 0.930 g/cm³.

In a particular embodiment of the abovementioned embodiment example, thelayer of thermoplastic KSa is present as a mixture of a polyolefinprepared by means of a metallocene catalyst and a further polymer, thefurther polymer preferably being a polyolefin which has not beenprepared by means of a metallocene catalyst, preferably a polyethylenewhich has not been prepared by means of a metallocene catalyst.Particularly preferably, the layer of thermoplastic KSa is present as amixture of 25 to 95 wt. %, preferably 35 to 85 wt. % and particularlypreferably 45 to 75 wt. % of mPE and 5 to 75 wt. %, preferably 15 to 65wt. % and particularly preferably 25 to 55 wt. % of PE, the mPEdescribed here fulfilling at least one, preferably at least two andparticularly preferably all of the parameters of Vicat softeningtemperature, melting temperature, MFR value and density mentioned abovefor the layer of thermoplastic KSv.

Plastics which have already been described for the layers ofthermoplastic KSu, KSv or KSa, in particular, can preferably be employedfor the layer of thermoplastic KSw, which preferably has a weight perunit area in a range of from 2 to 60 g/m², particularly preferably from5 to 50 g/m² and moreover preferably from 7 to 40 g/m². Furtherpreferably, the layer of thermoplastic KSw occurs as a mixture of atleast two thermoplastics.

According to a preferred embodiment, the layer of thermoplastic KSw isbased on a mixture of at least two polymers, one polymer preferablyhaving a density in a range of from 0.910 to 0.930 g/cm³, preferablyfrom 0.915 to 0.925 g/cm³. Furthermore preferably, this polymer has amelting temperature in a range of from 100° C. to 115° C. A secondpolymer preferably has a density in a range of from 0.880 to 0.915g/cm³, preferably 0.890 to 0.910 g/cm³ and particularly preferablyadditionally a melting temperature in a range of from 90° C. to 115° C.The layer KSw has a Vicat softening temperature in a range of from 60 to105° C., preferably from 65 to 100° C. and particularly preferably from70 to 95° C.

In a particular embodiment of the abovementioned embodiment example, thelayer of plastic KSw is present as a mixture of a polyolefin prepared bymeans of a metallocene catalyst and a further polymer, the furtherpolymer preferably being a polyolefin which has not been prepared bymeans of a metallocene catalyst, preferably a polyethylene which has notbeen prepared by means of a metallocene catalyst. Particularlypreferably, the layer of plastic KSw is present as a mixture of 65 to 95wt. %, preferably 70 to 90 wt. % and particularly preferably 75 to 85wt. % of mPE and 5 to 35 wt. %, preferably 10 to 30 wt. % andparticularly preferably 15 to 25 wt. % of PE. In a further embodimentexample, the layer of thermoplastic KSw is present as a mixture of 15 to45 wt. %, preferably 20 to 40 wt. % and particularly preferably 25 to 35wt. % of mPE and 55 to 85 wt. %, preferably 60 to 80 wt. % andparticularly preferably 65 to 75 wt. % of PE.

According to a further preferred embodiment variant, one or more or allof the layers of thermoplastic of the composite KSv, KSa, KSw andoptionally KSu can also comprise an inorganic solid as a filler, inaddition to a thermoplastic polymer. In this connection, it ispreferable for the particular layer of thermoplastic to comprise athermoplastic polymer or polymer mixture to the extent of at least 60wt. %, preferably at least 80 wt. % and particularly preferably at least95 wt. %, in each case based on the corresponding layer ofthermoplastic. All solids which seem suitable to the person skilled inthe art are possible as the inorganic solid, preferably particulatesolids, preferably metal salts or oxides of di- to tetravalent metals.Examples which may be mentioned here are the sulphates or carbonates ofcalcium, barium or magnesium or titanium dioxide, preferably calciumcarbonate. The average particle sizes (d50%) of the inorganic solids,determined by sieve analysis, are preferably in a range of from 0.1 to10 μm, preferably in a range of from 0.5 to 5 μm and particularlypreferably in a range of from 1 to 3 μM.

According to a further preferred embodiment, at least one, preferably atleast two and furthermore preferably at least three of the layers ofthermoplastic KSv, KSa, KSw or optionally KSu is a plastics mixture ofat least two plastics.

Preferably, at least one of the layers of thermoplastic KSv, KSa, KSw oroptionally KSu contains at least one polyolefin with a mass density in arange of from 0.918 g/cm³ to 0.980 g/cm³, preferably from 0.922 to 0.970g/cm³, particularly preferably from 0.925 to 0.965 g/cm³ and moreoverpreferably from 0.930 to 0.960 g/cm³ in a range of from 20 wt. % to 100wt. %, preferably from 45 to 95 wt. % and particularly preferably from65 to 85 wt. %, in each case based on the total weight of the layer ofplastic. Particularly preferably, one of the layers of thermoplastic KSvand KSa has, in particular, the abovementioned mass density. Accordingto a further preferred embodiment, both layers of thermoplastic KSv andKSa have a mass density in the abovementioned range. Particularlypreferably, the mass density of the layer of thermoplastic KSw does notlie in the range mentioned. According to a further preferred embodiment,the layers of thermoplastic KSv, KSa, KSw and optionally KSu each have amelting temperature in the range of from 80 to 155° C.

According to the invention, the Vicat softening temperature of the layerof thermoplastic KSv and the Vicat softening temperature of the layer ofthermoplastic KSa is in each case higher, particularly preferably by ineach case at least 4 K, at least 6 K, at least 8 K, at least 10 K, atleast 12 K, at least 14 K, at least 16 K or at least 18 K higher thanthe Vicat softening temperature of the layer of thermoplastic KSw.Maximum differences in the Vicat softening temperatures of 60 K areoften observed.

Further preferably, the Vicat softening temperature of the at least onelayer of thermoplastic KSv and of the at least one layer ofthermoplastic KSa is in each case in a range of from 90 to 150° C., orfrom 95 to 140° C. or from 100 to 135° C. The Vicat softeningtemperature of the at least one layer of thermoplastic KSw is preferablyin a range of from 60° C. to 105° C., or from 65° C. to 100° C. or from70° C. to 95° C.

According to a further preferred embodiment, the melting temperature ofthe layer of thermoplastic KSv and the melting temperature of the layerof thermoplastic KSa is in each case higher, particularly preferably byin each case at least 3 K, or 4 K, at least 6 K, at least 8 K, at least10 K, at least 12 K, at least 14 K, at least 16 K or at least 18 Khigher than the melting temperature of the layer of thermoplastic KSw.Further preferably, the melting temperature of the layer ofthermoplastic KSv and of the layer of thermoplastic KSa is in each casein a range of from 100 to 150° C., or from 105 to 140° C. The meltingtemperature of the layer of thermoplastic KSw is preferably in a rangeof from 80° C. to 125° C., or from 85° C. to 120° C., or from 90° C. to115° C.

According to a further preferred embodiment, the modulus of thedifference between the Vicat softening temperature of the layer ofthermoplastic KSv and the Vicat softening temperature of the layer ofthermoplastic KSa is in a range of from 0 to 10 K, or in a range of from0 to 5 K, or in a range of from 0 to 3 K or in a range of from 0.1 to1.8 K.

According to a further preferred embodiment, the modulus of thedifference between the melting temperature of the layer of thermoplasticKSv and the melting temperature of the layer of thermoplastic KSa is ina range of from 0 to 10 K, or in a range of from 0 to 5 K, or in a rangeof from 0 to 3 K or in a range of from 0.1 to 1.8 K.

Possible adhesion promoters in the adhesion promoter layer are allplastics which, due to functionalization by means of suitable functionalgroups, are suitable for generating a firm join by the formation ofionic bonds or covalent bonds to the surface of the other particularlayer. Preferably, these are functionalized polyolefins which have beenobtained by copolymerization of ethylene with acrylic acids, such asacrylic acid, methacrylic acid, crotonic acid, acrylates, acrylatederivatives or carboxylic acid anhydrides carrying double bonds, forexample maleic anhydride, or at least two of these. Among these,polyethylene-maleic anhydride graft polymers (EMAH), ethylene/acrylicacid copolymers (EAA) or ethylene/methacrylic acid copolymers (EMAA),which are marketed, for example, under the trade names Bynel® andNucrel® 0609HSA by DuPont or Escor® 6000ExCo by ExxonMobile Chemicals,are preferred.

In one embodiment of the process according to the invention, it ispreferable, for further improvement in the adhesion of two adjacentlayers to one another, for these to be subjected to a surface treatment,for example, during the coating. Suitable processes for the surfacetreatment are a flame treatment, a treatment with plasma, a coronatreatment or a treatment with ozone known, inter alia, to the personskilled in the art. However, other processes which have the effect offormation of functional groups on the surface of the treated layer arealso conceivable. In a particular embodiment, at least one of theseprocesses is used in the lamination of metal layers, in particular ofmetal foils.

In order to facilitate the ease of opening of the container according tothe invention, the carrier layer can have at least one hole. In aparticular embodiment, the hole is covered at least with the barrierlayer and at least one of the layers of thermoplastic KSa or KSw ashole-covering layers.

According to a further preferred embodiment, the carrier layer ofcomposite has a hole which is covered at least with the layer ofthermoplastic KSv, the barrier layer and the layers of thermoplastic KSaand KSW as hole-covering layers. It is particularly preferable for thehole additionally to be covered with the layer of thermoplastic KSu. Itis particularly preferable for the hole additionally to be covered withthe layer of thermoplastic KSu. One or more further layers, inparticular adhesion promoter layers, can furthermore be provided betweenthe layers already mentioned. It is preferable here for. Thehole-covering layers to be joined to one another at least partly,preferably to the extent of at least 30%, preferably at least 70% andparticularly preferably to the extent of at least 90% of the area formedby the hole. According to a particular embodiment, however, it may bethat the hole penetrates through the entire composite and is covered bya closure or opening device which closes the hole.

In connection with a first preferred embodiment, the hole provided inthe carrier layer can have any form which is known to the person skilledin the art and is suitable for various closures, drinking straws oropening aids.

The opening of such a container is usually generated by at least partialdestruction of the hole-covering layers covering the hole. Thisdestruction can be effected by cutting, pressing into the container orpulling out of the container. The destruction can be effected by anopenable closure joined to the container and arranged in the region ofthe hole, usually above the hole, or a drinking straw which is pushedthrough the hole-covering layers covering the hole.

According to a further preferred embodiment, the carrier layer of thecomposite has a plurality of holes in the form of a perforation, theindividual holes being covered at least with the barrier layer and oneof the layers of thermoplastic KSa and KSw as hole-covering layers. Acontainer produced from such a composite can then be opened by tearingalong the perforation. Such holes for perforations are preferablygenerated by means of a laser. The use of laser beams is particularlypreferred if a metal foil or a metallized foil is employed as thebarrier layer. It is furthermore possible for the perforation to beintroduced by mechanical perforation tools, usually having blades.

According to a further preferred embodiment, the sheetlike composite issubjected to a heat treatment at least in the region of the at least onehole. In the case of several holes present in the carrier layer in theform of a perforation, it is particularly preferable for this heattreatment also to be carried out around the edge region of the hole.

The heat treatment can be carried out by radiation, by hot gas, bythermal contact with a solid, by mechanical vibrations or by acombination of at least two of these measures. Particularly preferably,the heat treatment is carried out by irradiation, preferablyelectromagnetic radiation and particularly preferably electromagneticinduction or also by hot gas. The particular optimum operatingparameters to be chosen are known to the person skilled in the art.

According to a further preferred embodiment, the plastics of the layersof thermoplastic of the sheetlike composite, in particular the layers ofthermoplastic KSv and KSa, contain no comonomers which are known to theperson skilled in the art to have the effect of an improvement inadhesion. Such copolymers are mentioned inter alia in the abovementionedadhesion promoter layers. In particular, the layers of thermoplastic KSvand KSa are therefore as a rule not suitable as adhesion promoters or asadhesive layers.

The present invention also provides a process for the production of thesheetlike composite described above. All the processes which are knownto the person skilled in the art and seem suitable for the production ofthe composite according to the invention are possible for this.

According to preferred embodiment, the sheetlike composite according tothe invention can be produced by a process which comprises, inter alia,the following process steps:

-   -   A. provision of a composite precursor comprising at least the        carrier layer;    -   B. application of at least one layer of thermoplastic to one        side of the composite precursor;    -   C. application of at least one further layer of thermoplastic to        the opposite side of the composite precursor.

In process step A. of the process according to the invention, acomposite precursor comprising at least the carrier layer is firstproduced. The composite precursor essentially includes the carrierlayer, which can already have one or more holes and to which optionallyat least one printed layer is applied. Preferably, however, thiscomposite precursor is a non-printed carrier layer.

In step B. at least one layer of thermoplastic is applied to thecomposite precursor provided. The application of this at least one layeris preferably carried out by melt coating, preferably by extrusioncoating. However, it is also conceivable for several layers, for examplelayers of thermoplastic, barrier layers and/or adhesion promoter layers,to be applied sequentially or simultaneously by coextrusion in step B.

In step C. at least one further layer of thermoplastic is then appliedto the opposite side of the composite precursor. The application of thisat least one further layer of thermoplastic is preferably carried out bymelt coating, preferably by extrusion coating. However, it is alsoconceivable for several layers, for example layers of thermoplastic,barrier layers and/or adhesion promoter layers, to be appliedsequentially or simultaneously by coextrusion in step C.

During application of the individual layers, in a preferred embodimentthe at least one film or a multilayer composite film is provided in theform of a roll and is laminated on to the composite via further layers,preferably layers of thermoplastic or adhesion promoter layers. This isthe case in particular during introduction of metal layers, inparticular of metal foils.

If the sheetlike composite has one or more holes to facilitate ease ofopening, these can be introduced into the sheetlike composite eitherbefore step A., after step B. or after step C.

In a preferred embodiment of the process, a non-printed carrier layerwhich already has holes is provided as the composite precursor in stepA. In step B. the layer of thermoplastic KSu is then first applied tothe composite precursor. In the further process step C. the layer ofthermoplastic KSv, the barrier layer, the layer of thermoplastic KSa andthe layer of thermoplastic KSw are then applied. In each case one ormore adhesion promoter layers can also be co-applied here. In anotherembodiment, however, it is also conceivable that in step B. first thelayer of thermoplastic KSv, the barrier layer, the layer ofthermoplastic KSa and the layer of thermoplastic KSw are applied. Instep C. the layer of thermoplastic KSu is then applied. Here also, ineach case further layers, for example adhesion promoter layers, can beco-applied. The extrusion can be carried out in individual layers by aseries of successive individual extruders or also in multiple layers bycoextrusion, the abovementioned sequence of the individual layers alwaysbeing retained. A combination of extrusion and lamination coating canalso take place in the process according to the invention.

In connection with the sheetlike composite, but also in connection withthe composite precursor, it is preferable for at least one of the two tohave at least one or two and more scores along which edges are formedduring production of the container. This facilitates the folding and theformation of a kink running along the line prepared by the score, inorder to achieve in this way a fold which is as uniform and accuratelypositioned as possible. The scores can be introduced already before stepA, after step B or also after step C, it being preferable for thescoring to be carried out after step C, that is to say after the coatingof both sides of the carrier layer.

As a rule, the sheetlike composite is produced, usually as roll goods,by coextrusion of the individual layers of the sheetlike composite. Thescores are provided on these roll goods. However, it is also possiblefor the scores to be produced in the carrier layer already before thecoating.

According to a further preferred embodiment of the process according tothe invention for the production of a sheetlike composite, it ispreferable, especially if the carrier layer, as described above,includes a hole or several holes, for at least one of the layers ofplastic KSv, KSa, KSw or optionally KSu to be stretched during theapplication, this stretching preferably being carried out by meltstretching, very particularly preferably by monoaxial melt stretching.For this, the layer is applied in the molten state to the compositeprecursor by means of a melt extruder and the layer applied, which isstill in the molten state, is then stretched in preferably the monoaxialdirection in order to achieve an orientation of the polymer in thisdirection. The layer applied is then allowed to cool for the purpose ofthermofixing.

In this connection, it is particularly preferable for the stretching tobe carried out by at least the following application steps:

-   b1. emergence of the at least one layer of thermoplastic as at least    one melt film via at least one extruder die slot with an exit speed    V_(exit);-   b2. application of the at least one melt film to the composite    precursor moving relative to the at least one extruder die slot with    a moving speed V_(adv);    where V_(exit)<V_(adv). It is particularly preferable for V_(adv),    to be greater than V_(exit) by a factor in the range of from 5 to    200, particularly preferably in a range of from 7 to 150, moreover    preferably in a range of from 10 to 50 and most preferably in a    range of from 15 to 35. In this context, it is preferable for    V_(adv), to be at least 100 m/min, particularly preferably at least    200 m/min and very particularly preferably at least 350 m/min, but    conventionally not to lie above 1,300 m/min.

After the melt layer has been applied to the composite precursor bymeans of the stretching process described above, the melt layer isallowed to cool for the purpose of thermofixing, this cooling preferablybeing carried out by quenching via contact with a surface which is keptat a temperature in a range of from 5 to 50° C., particularly preferablyin a range of from 10 to 30° C.

As already described above, after the thermofixing it may prove to beparticularly advantageous if the sheetlike composite is heat-treated atleast in the region of the at least one hole, in order to effect therean at least partial elimination of the orientation of the polymer.

According to a further preferred embodiment, at least one, preferablytwo or even all of the layers of thermoplastic KSv, KSa, KSw oroptionally KSu is produced by extrusion or coextrusion of at least onepolymer P1 through a slot die to obtain an emerging surface, at leastone polymer P2 which differs from polymer P1 being provided on theflanks of the surface of the at least one polymer P1 emerging from theslot die. Thermoplastic polymers are preferably chosen as the polymerP2. Preferred thermoplastic polymers have a high rate of branching, awide molecular weight distribution, and in the case of extrusioncoating, after exit from the die have a low tendency towards “neck-in”and “edge-waving” or film striking.

The preferred embodiments relating to the production of the sheetlikecomposite employing at least one or more up to even all of the layers ofthermoplastic from thermoplastics which can be produced by extrusion orcoextrusion have already been described above. The choice ofthermoplastic to be employed depends on which of the layers ofthermoplastic KSu, KSv, KSa or KSw is to be produced by extrusion orcoextrusion. With respect to the suitable and preferred thermoplastics,reference is made to the description of the layers of plastic KSu, KSv,KSa and KSw. The thermoplastic chosen or the mixture of thermoplasticschosen then forms P1 of the particular layer of thermoplastic. During acoextrusion of different layers, the surface F is formed from severaldifferent thermoplastics or plastics mixtures P1.

With respect to an efficient use of materials, in a preferred embodimentthe polymer P2 can likewise also be a constituent of the surface F. Oneor more thermoplastics, preferably polyethylenes, particularlypreferably LDPE and moreover preferably LDPE prepared in an autoclavereactor, are particularly suitable as polymer P2. By way of example,suitable polymers are 23L430 or 19N430 from Ineos. It is alsoconceivable for a mixture of at least two suitable polymers to beemployed as the edge layer P2.

The polymer P1 and the polymer P2 are preferably coextruded. They thusform intimately bonded regions of the emerging surface. There areessentially two variants here of how the polymer stream P2 can be fed tothe extruder die. If the P2 is also a constituent of the film F, thiscan be branched off into a separate polymer stream in the feed block andpassed to the edge region of the extruder die. Alternatively, anadditional extruder which provides the P2 and leads it to the extruderdie can also be provided.

During the extrusion, the thermoplastics are conventionally heated totemperatures of from 210 to 330° C., measured on the molten polymer filmbelow the exit at the extruder die. The extrusion can be carried out bymeans of extrusion tools which are known to the person skilled in theart and commercially obtainable, such as, for example, extruders,extruder screws, feed block etc.

According to a further preferred embodiment, the area which has emergedis cooled to a temperature below the lowest melting temperature of thepolymers P1 and P2 provided in this surface or its flanks, and at leastthe flanks of the surface are then separated off from this surface.Cooling can be carried out in any manner which is familiar to the personskilled in the art and seems to be suitable. The thermofixing alreadydescribed above is also preferred here. At least the flanks are thenseparated off from the surface F. The separating off can be carried outin any manner which is familiar to the person skilled in the art andseems to be suitable. Preferably, the separating off is carried out by aknife, laser beam or water jet, or a combination of two or more ofthese, the use of knives, in particular knives for a shear cut, beingparticularly preferred.

The present invention also provides a container which surrounds aninterior and comprises at least the sheetlike composite described above.The embodiments, and in particular the preferred embodiments, describedin connection with the sheetlike composite according to the inventionare also preferred for the container according to the invention.

The present invention also provides a process for the production of acontainer surrounding an interior, comprising the process steps,preferably in the sequence shown:

-   a. provision of a sheetlike composite comprising a layer    configuration with the following layers:    -   o. optionally a layer of thermoplastic KSu of a plastics        composition KSum;    -   i. a carrier layer;    -   ii. a first layer of thermoplastic KSv of a plastics composition        KSvm;    -   iii. a barrier layer;    -   iv. a second layer of thermoplastic KSa of a plastics        composition KSam;    -   v. a further layer of thermoplastic KSw of a plastics        composition KSwm;-    wherein the Vicat softening temperature of the plastics composition    KSvm and the Vicat softening temperature of the plastics composition    KSam is in each case higher than the Vicat softening temperature of    the plastics composition KSwm;-   b. folding of the sheetlike composite to form a fold with at least    two fold surfaces adjacent to one another, layer v. facing the    interior of the container;-   c. joining of in each case at least a part region of the at least    two fold surfaces to form a container region.

The plastics compositions employed according to the invention can bemade of a single thermoplastic or from two or more thermoplastics. Theabove statements therefore apply here accordingly to the thermoplasticsand the layers of thermoplastic. Generally, the plastics compositionscan be fed to an extruder in any form which is suitable for extruding tothe person skilled in the art. Preferably, the plastics compositions areemployed as powders or granules, preferably as granules.

The embodiments, and in particular the preferred embodiments, describedin connection with the sheetlike composite according to the inventionare also preferred in the process according to the invention for theproduction of the container surrounding an interior. It is particularlypreferable for the Vicat softening temperature of the plasticscomposition KSvm and the Vicat softening temperature of the plasticscomposition KSam also in each case to be higher than the Vicat softeningtemperature of the plastics composition KSwm.

In the process according to the invention, it is furthermore preferablefor the Vicat softening temperature of the plastics composition KSvm andthe Vicat softening temperature of the plastics composition KSam in eachcase to be higher, particularly preferably by in each case at least 4 K,at least 6 K, at least 8 K, at least 10 K, at least 12 K, at least 14 K,at least 16 K or at least 18 K, than the Vicat softening temperature ofthe plastics composition KSwm.

The embodiments, and in particular the preferred embodiments, describedin connection with the sheetlike composite according to the inventionare also preferred in the process according to the invention for theproduction of the container surrounding an interior.

If the roll goods provided with scores are not employed directly in stepa., container blanks for an individual container are obtained from theroll goods and are provided as the sheetlike composite in step a.

The container according to the invention can have a large number ofdifferent forms, but an essentially square-shaped structure ispreferred. The container can furthermore be formed over its completesurface from the sheetlike composite, or can have a 2- or multi-partconfiguration. In the case of a multi-part configuration, it isconceivable that in addition to the sheetlike composite, other materialscan also be employed, for example plastic material, which can beemployed in particular in the top or the base regions of the container.However, it is preferable here for the container to be constructed fromthe sheetlike composite to the extent of at least 50%, particularlypreferably to the extent of at least 70% and moreover preferably to theextent of at least 90% of the surface. Furthermore, the container canhave a device for emptying the contents. This can be formed, forexample, from plastic material and attached to the outside of thecontainer. It is also conceivable that this device is integrated intothe container by “direct injection moulding”.

According to a preferred embodiment, the container according to theinvention has at least one, preferably from 4 to 22 or also more edges,particularly preferably from 7 to 12 edges. In the context of thepresent invention, edge is understood as meaning regions which areformed on folding a surface. Edges which may be mentioned by way ofexample are the elongated contact regions of in each case two wallsurfaces of the container. In the container, the container wallspreferably represent the surfaces of the container framed by the edges.

In process step a. of the process according to the invention, asheetlike composite obtained by the process described above for theproduction of a sheetlike composite is first provided, from which acontainer precursor is then formed by folding in process step b.

In one embodiment of the process according to the invention, in step b.the at least one, preferably at least two of the layers of thermoplasticKSv, KSa, KSw and optionally KSu, further preferably at least the layersof thermoplastic KSa and KSw, and particularly preferably each of thelayers of thermoplastic KSv, KSa, KSw and optionally KSu, has atemperature above the melting temperature of the particular layer.

In another embodiment of the process according to the invention, in stepb. the at least one, preferably at least two of the layers ofthermoplastic KSv, KSa, KSw and optionally KSu, further preferably atleast the layers of thermoplastic KSa and KSw, and particularlypreferably each of the layers of thermoplastic KSv, KSa, KSw andoptionally KSu, has a temperature below the melting temperature of theparticular layer.

According to a further preferred embodiment of the process according tothe invention, at least one, preferably at least two of the layers ofthermoplastic KSv, KSa, KSw and optionally KSu, further preferably atleast the layers of thermoplastic KSa and KSw, or also all of the layersof thermoplastic KSv, KSa, KSw and optionally KSu has or have a meltingtemperature below the melting temperature of the barrier layer.

The melting temperatures of the at least one, preferably of the at leasttwo, further preferably at least the layers of thermoplastic KSa and KSwor also all of the layers of thermoplastic KSv, KSa, KSw and optionallyKSu and the melting temperature of the barrier layer differ herepreferably by at least 1 K, particularly preferably by at least 10 K,still more preferably by at least 50 K, moreover preferably at least 100K. The temperature difference should preferably be chosen only so highthat melting of the barrier layer, in particular melting of the barrierlayer of plastic, does not occur during the folding.

In the process according to the invention, in a further embodiment afurther folding follows step c. as step d., in the further folding atleast one, preferably each of the layers of thermoplastic KSv, KSa, KSwand optionally KSu having a temperature which is below the meltingtemperature of this layer of thermoplastic.

According to the invention, in this context “folding” is understood asmeaning an operation in which preferably an elongated kink forming anangle is generated in the folded sheetlike composite by means of afolding edge of a folding tool. For this, two adjacent surfaces of asheetlike composite are often bent ever more towards one another. By thefold, at least two adjacent fold surfaces are formed, which can then bejoined at least in part regions to form a container region. According tothe invention, the joining can be effected by any measure which appearsto be suitable to the person skilled in the art and which makes possiblea join which is as gas- and liquid-tight as possible. The joining can becarried out by sealing or gluing or a combination of the two measures.In the case of sealing, the join is created by means of a liquid andsolidification thereof. In the case of gluing, chemical bonds whichcreate the join form between the interfaces or surfaces of the twoobjects to be joined. In the case of sealing or gluing, it is oftenadvantageous for the surfaces to be sealed or glued to be pressedtogether with one another.

The sealing temperature is preferably chosen such that the thermoplasticor thermoplastics involved in the sealing, preferably the polymers ofthe layer of thermoplastic KSw and/or optionally of the layer ofthermoplastic KSu, are present as a melt. The sealing temperatures aretherefore at least 1 K, preferably at least 5 K and particularlypreferably at least 10 K above the melting temperature of the particularplastic. Furthermore, the sealing temperature chosen should not be toohigh, in order that the exposure of the plastic or plastics to heat isnot unnecessarily severe, so that they do not lose their envisagedmaterial properties.

In a further preferred embodiment of the process according to theinvention, it is envisaged that the container is filled with a foodstuffbefore step b. or after step c. All the foodstuffs known to the personskilled in the art for human consumption and also animal feeds arepossible as the foodstuff. Preferred foodstuffs are liquid above 5° C.,for example dairy products, soups, sauces and non-carbonated drinks. Thefilling can be carried out in various ways. On the one hand, thefoodstuff and the container can be sterilized separately, before thefilling, to the greatest degree possible by suitable measures such astreatment of the container with H₂O₂, UV radiation or other suitablehigh-energy radiation, plasma treatment or a combination of at least twoof these, as well as heating of the foodstuff, and the container is thenfilled. This type of filling is often called “aseptic filling” and ispreferred according to the invention. In addition to or also instead ofthe aseptic filling, it is furthermore a widespread procedure to heatthe container filled with foodstuff to reduce the germ count. This ispreferably carried out by pasteurization or autoclaving. Less sterilefoodstuffs and containers can also be employed in this procedure.

In the embodiment of the process according to the invention in which thecontainer is filled with foodstuff before step b., it is preferable fora tubular structure with a fixed longitudinal seam first to be formedfrom the sheetlike composite by sealing or gluing the overlappingborders. This tubular structure is compressed laterally, fixed andseparated and formed into an open container by folding and sealing orgluing. The foodstuff here can already be filled into the containerbefore the fixing and before the separation and folding of the base inthe sense of step b.

In the embodiment of the process according to the invention in which thecontainer is filled with foodstuff after step c., it is preferable for acontainer which is obtained by shaping the sheetlike composite and isopened on one side to be employed. Shaping of the sheetlike compositeand obtaining of such an opened container can be carried out by steps b.and c. by any procedure which appears to be suitable for this to theperson skilled in the art. In particular, shaping can be carried out bya procedure in which sheet-like container blanks which already take intoaccount the shape of the container in their cut-out are folded such thatan opened container precursor is formed. This is as a rule effected by aprocedure in which after folding of this container blank, itslongitudinal edges are sealed or glued to form a side wall and the oneside of the container precursor is closed by folding and further fixing,in particular sealing or gluing.

In a further embodiment of the process according to the invention, it ispreferable for the fold surfaces to form an angle μ of less than 90°,preferably of less than 45° and particularly preferably of less than20°. The fold surfaces are often folded to the extent that these come tolie on one another at the end of the folding. This is advantageous inparticular if the fold surfaces lying on one another are subsequentlyjoined to one another in order to form the container base and thecontainer top, which is often configured gable-like or also flat.Regarding the gable configuration, reference may be made by way ofexample to WO 90/09926 A2.

Furthermore, in one embodiment of the process according to theinvention, at least the layer of thermoplastic KSw or optionally thelayer of thermoplastic KSu or also both, is or are heated above themelting temperature of the layers of thermoplastic before step c.Preferably, before step c., particularly preferably directly before stepc., heating is carried out to temperatures which are at least 1 K,preferably at least 5 K and particularly preferably at least 10 K abovethe melting temperature of these layers. The temperature should as faras possible be above the melting temperature of the particular plasticto the extent that by the cooling, due to the folding, moving andpressing, the plastic does not cool to the extent that this becomessolid again.

Preferably, the heating to these temperatures is carried out byirradiation, by mechanical vibrations, by contact with a hot solid orhot gas, preferably hot air, or a combination of these measures. In thecase of irradiation, any type of radiation which is suitable forsoftening the plastics to the person skilled in the art is possible.Preferred types of radiation are IR rays, UV rays, microwaves or alsoelectromagnetic radiation, in particular electromagnetic induction.Preferred types of vibration are ultrasound.

In the process according to the invention, it is furthermore preferablefor the maximum transmission intensity of at least one of the perforatedcovering layers comprising a stretched polymer to differ before andafter the heat treatment. This can conventionally be ascertained bydifferent representations of the region viewed through a polarizationfilter. The heat-treated regions thus differ by light-dark contrastsfrom the regions on a surface which are adjacent to these but have notbeen heat-treated. Moreover, a difference in gloss is generally to bedetected due to the change in structure of the polymer inner layeroriginating from the heat treatment, compared with the regions whichhave not been heat-treated. The same applies to regions before and afterthe heat treatment.

In addition to the perforated covering layers, further regions of thesheetlike composite can also be heat-treated. These also show adifferent maximum transmission intensity compared with the non-treatedregions. These include all regions in which joining by sealing iscarried out and/or scores for folding are provided. Among these regions,the longitudinal seams at which the sheetlike composite is formed into atubular or jacket-like structure are particularly preferred. After theabove heat treatment, the heat-treated regions can be allowed to coolagain.

According to the above embodiments, the invention also provides the useof the sheetlike composite according to the invention or of a containerproduced therefrom or comprising this composite for storage offoodstuffs, in particular of sterilized foodstuffs.

Test Methods:

Unless specified otherwise herein, the parameters mentioned herein aremeasured by means of ISO specifications. These are, for determination of

-   -   the MFR value: ISO 1133 (unless otherwise stated, at 190° C. and        2.16 kg);    -   the density: ISO 1183-1;    -   the melting temperature with the aid of the DSC method: ISO        11357-1, -5; if the sample is based on a mixture of several        plastics and the determination of the melting temperature by the        abovementioned method gives several peak temperatures T_(p), the        highest of the peak temperatures T_(p,m) which is to be assigned        to a plastic of the plastics mixture is defined as the melting        temperature. The equipment is calibrated according to the        manufacturer's instructions with the aid of the following        measurements:        -   indium onset temperature        -   heat of melting of indium        -   zinc onset temperature    -   the molecular weight distribution by gel permeation        chromatography by means of light scattering: ISO 16014-3/-5;    -   the viscosity number of PA: ISO 307 in 95% sulphuric acid;    -   the oxygen permeation rate: ISO 14663-2 annex C at 20° C. and        65% relative atmospheric humidity;    -   the Vicat softening temperature: ISO 306:2004, method VST-A50        (load=10 N, increase in temperature=50 K/h) using an oil heating        bath;    -   the moisture content of the cardboard: ISO 287:2009;    -   the extensibility or tensile strength of the aluminium foil: ISO        546-1;    -   For determination of the adhesion of two adjacent layers, these        are fixed on a rotatable roll on a 90° peel test apparatus, for        example from Instron “German rotating wheel fixture”, which        rotates at 40 mm/min during the measurement. The samples were        cut to size in 15 mm wide strips beforehand. On one side of the        sample the layers are detached from one another and the detached        end is clamped in a tensioning device directed perpendicularly        upwards. A measuring apparatus for determining the tensile force        is attached to the tensioning device. On rotation of the roll,        the force necessary to separate the layers from one another is        measured. This force corresponds to the adhesion of the layers        to one another and is stated in N/15 mm. The separation of the        individual layers can be carried out, for example, mechanically,        or by a targeted pretreatment, for example by softening the        sample for 3 min in 60° C. hot 30% acetic acid.    -   For determination of the Vicat softening temperature on        individual layers of the composite, the layer to be investigated        is separated from the remaining layers by mechanical or chemical        means. It is essential to ensure here that no contamination of        the samples by adjacent layers occurs. From the sample material        collected in this way, a test specimen can be established        according to the dimensions stated in ISO 306:2004 and the Vicat        softening temperature can be determined in accordance with the        standard mentioned. If the material of plastic to be        investigated is present as flocks or crumbs, these are processed        to give a homogeneous test specimen. This can be carried out by        pressing, careful heating or both measures.

EXAMPLE

The sheetlike composites were produced with the aid of the coatingprocess described above by process steps A-C. A carrier layer whichoptionally has holes for closures or drinking straws is first taken.This is first coated according to process step A with the layer ofplastic KSu, and in process step C first the layer of plastic KSv, theadhesion promoter layer and then the barrier layer, followed by anadhesion promoter layer of the layer of plastic KSa and finally thelayer of plastic KSw are then applied to the side of the carrier layerfacing away from the layer of plastic KSu. This is as a rule carried outin a commercially available coating installation.

Weight per unit area Layer or film thickness KSu 20 g/m² 100 wt. % (4)Carrier layer 220 g/m² (2) KSv 18 g/m²  70 wt. % (5)/30 wt. % (4)Adhesion promoter 3 g/m² 100 wt. % (8) Barrier layer 6 μm (1) Adhesionpromoter 4 g/m² 100 wt. % (7) KSa 22 g/m²  70 wt. % (5)/30 wt. % (4) KSw10 g/m²  70 wt. % (3)/30 wt. % (6) (1) Aluminium foil, EN AW 8079,tensile strength: 75 N/mm², extensibility: 1.7% from Hydro AluminiumDeutschland GmbH (2) Cardboard, Stora Enso Natura (3) 19N430 from Ineos(4) 23L430 from Ineos (5) Lumicene ® mPE M 4040 from TotalPetrochemicals (6) Affinity ® PT 1451G1 from Dow Chemicals (7) Escor6000 HSC ExxonMobile (8) Novex M21N430 from Ineos

FIGURES

The present invention is now explained in more detail by these drawingsgiven by way of example which do not limit it, the figures showing

1 a schematic view of a container produced by the process according tothe invention,

2 a schematic illustration of the process flow of the process accordingto the invention,

3 a schematic view of a region of a container to be produced by theprocess according to the invention,

4 a a schematic illustration of folding by the process according to theinvention,

4 b a schematic illustration of a fold by the process according to theinvention,

5 a a schematic illustration along a section A-A in the unfolded state,

5 b a schematic illustration along a section A-A in the folded state,

6 a schematic illustration of a sheetlike composite which can beemployed in the process according to the invention,

7 a schematic illustration of a sheetlike composite which can beemployed in the process according to the invention,

8 a a schematic illustration of a sonotrode-anvil arrangement before thesealing,

8 b a schematic illustration of a sonotrode-anvil arrangement during andat the end of the sealing,

9 a extrusion process (top view)

9 b extrusion process (side view)

FIG. 1 shows a container 2 surrounding an interior 1 and made of asheetlike composite 3. The container 2 is shown with the container upperside 12 facing upwards. The container 2 is made of the sheetlikecomposite 3 which includes at least the carrier layer 4. The container 2can furthermore include a hole 36.

FIG. 2 shows a schematic flow of devices and production steps by theprocess according to the invention. In a composite production 20, thesheetlike composite 3 is thus produced from a carrier layer 4, a barrierlayer 5 and the layers of thermoplastic KSa 6, KSv 35 and KSw 7 andoptionally a further layer of thermoplastic KSu 13 and—if necessary—atleast one adhesion promoter layer 19 by an extrusion process and isusually provided as roll goods. In a composite fabrication 21 whichfollows the composite production 20 indirectly or directly, the score 14is produced in the roll goods, which can have been provided with animprint or decoration beforehand. Furthermore, if the roll goodsprovided with scores 14 are not employed as such for the production ofcontainers, container blanks are produced in the composite fabrication21. The composite fabrication 21 is followed by a container production22, in which in particular the folding and joining are carried out bythe process according to the invention. Filling with a foodstuff canalso be carried out here.

FIG. 3 shows a container 2 formed during the process according to theinvention, which—for a better view—is shown with a container region 23envisaged for a base 12 on the top. The container region 23 envisagedfor the base 12 has a plurality of scores 14.

FIG. 4 a shows the cross-section through a sheetlike composite 3 with ascore 14, formed by a recess 24 and a bulge 25. An edge 17 of a foldingtool 18 is provided above the recess 24, in order to engage in therecess 24, so that folding can be carried out around the edge 17 alongthe score 14, in order to obtain a fold 8 shown as a cross-section inFIG. 4 b. This fold 8 has two fold surfaces 9 and 10 which enclose anangle g and are present as a part 15 of large area and a part 16 ofsmall area. At least one layer of thermoplastic 6, 7 or 13 is melted ina part region 11 of the part 16 of small area. By pressing the foldsurfaces 9, 10 together, reducing the angle μ, to 0°, the two foldsurfaces 9, 10 are joined to one another by sealing.

FIG. 5 a shows a section along the line A-A in FIG. 3, before folding,from a sheetlike composite 3 with scores 14. By edges 17 of foldingtools 18 which engage in the scores 14 installed centrally on the frontfaces, the scores 14 are moved in the direction of the two arrows, as aresult of which the folds 8 shown in FIG. 5 b with the angles μ areformed. The section shown here through the outermost part to be foldedof the container region envisaged for the base 12 of the container 2 hasa part region 11 towards the interior 1 in which at least one layer ofthermoplastic 6, 7 or 13 is melted. By pressing together thelongitudinal sides 26, reducing the six angles μ to 0, the two innersurfaces 27 of the longitudinal sides 26 facing the interior 1 arejoined to one another by sealing, in order thus to create the base 12.

FIG. 6 shows a sheetlike composite 3, the upper side lying on theoutside of the container 2 produced therefrom and the under-side on theinside. The resulting construction from the outside inwards is asfollows: layer of thermoplastic KSu 13 (usually PE optionally with afiller content of an inorganic salt) with a weight per unit area in arange of from 8 to 60 g/m², followed by a carrier layer 4 of cardboardwith a weight per unit area in a range of from 120 to 400 g/m², followedby a layer of thermoplastic KSv 35, usually with a weight per unit areain a range of from 5 to 40 g/m², followed by a barrier layer 5, forexample a barrier of plastic, with a weight per unit area in a range offrom 2 to 120 g/m², followed by a layer of adhesion promoter 19 with aweight per unit area in a range of from 2 to 30 g/m², optionallyfollowed by a layer of thermoplastic KSa 6, usually of PE, with a weightper unit area in a range of from 5 to 40 g/m², followed by a furtherlayer of thermoplastic KSw 7, usually of a blend of PE and mPE, with aweight per unit area in a range of from 2 to 60 g/m².

In FIG. 7, the sheetlike composite from FIG. 6 is supplemented by afurther layer 19 of adhesion promoter with a weight per unit area in arange of from 2 to 30 g/m² provided between the barrier layer 5, forexample of a metal layer with a thickness of 3-12 μm, and the carrierlayer 4.

FIG. 8 a shows a folded composite region 30 of the sheetlike composite 3between a sonotrode 28 and an anvil 34, both of which each have asurface relief 29. The folded composite region is formed by furtherreduction of the angle μ. in the context of the folding shown in FIG. 5b and often has an intermediate space 33 in the regions with few layers.The surface relief 29 is configured such that recesses 33 in the surfacerelief 29 are opposite the multilayer regions 31 of greater thicknessformed during folding, in order to allow a distribution of pressure andmechanical vibration over the sonotrode 28 which is as uniform aspossible. Furthermore, the fixing of the folded composite region 30 tobe joined, until the intermediate space 33 disappears, is improved inthis way. The sonotrode 28 moves to the anvil 34 in the direction of thearrow, a pressure acting on the folded composite region 30 to be joined,which is held between the surface reliefs 29. By this means, the foldedcomposite region, as shown in FIG. 8 b, is pressed together and heldaccording to the surface relief, so that the mechanical ultrasoundvibration generated by the sonotrode 28 is transmitted to the foldedcomposite 30 and joining by sealing takes place, in that the moltenlayers of plastic at least partly flow into one another due to thepressing pressure and solidify again by cooling, usually in a holdingtime, before the sonotrode 28 has released the folded composite region30 treated in this way.

FIG. 9 shows the coating process preferred according to the inventionschematically a. in the front view and b. in the side view. The coatingfilm in the molten state 39 exits the extruder die slot 38 of theextruder die 37 and is applied to the carrier layer 4 via the coolingand pressing rolls 41. The coating film forms the surface F whichcomprises the polymers P1 42 and P2 43, the polymer P2 43 forming theedge regions of the surface F. The edge surfaces P2 43 of the surface Fare preferably separated off from the surface F by cutting tools 44,preferably shearing blades. The molten coating film 39 exits theextruder die 37 with the speed V_(exit) and is accelerated to the speedV_(adv) by the cooling and pressing rolls and thus stretchedmonoaxially.

List of Reference Symbols 1 Interior 23 Container region 2 Container 24Recess 3 Sheetlike composite 25 Bulge 4 Carrier layer 26 Longitudinalsides 5 Barrier layer 27 Inner surface 6 Layer of thermoplastic KSa 28Sonotrode 7 Layer of thermoplastic KSw 29 Surface relief 8 Fold 30Folded composite region 9 Fold surface 31 Multilayer region 10 Furtherfold surface 32 Intermediate space 11 Part region 33 Recesses 12Container upper side 34 Anvil 13 Layer of thermoplastic KSu 35 Layer ofthermoplastic KSv 14 Score 36 Opening/perforation 15 Part with largearea 37 Extruder die 16 Part with small area 38 Extruder die slot 17Edge 39 Coating film (molten) 18 Folding tool 40 Coating film(thermofixed) 19 Adhesion promoter 41 Cooling roll, pressing roll 20Composite production 42 Polymer P1 21 Composite fabrication 43 PolymerP2 22 Container production 44 Cutting device

1. A sheetlike composite comprising a layer configuration with thefollowing layers: o. optionally a layer of thermoplastic KSu; i. acarrier layer; ii. a first layer of thermoplastic KSv; iii. a barrierlayer; iv. a second layer of thermoplastic KSa; and v. at least onefurther layer of thermoplastic KSw; wherein the Vicat softeningtemperature of the layer of thermoplastic KSv and the Vicat softeningtemperature of the layer of thermoplastic KSa is in each case higherthan the Vicat softening temperature of the layer of thermoplastic KSw.2. The sheetlike composite according to claim 1, wherein the Vicatsoftening temperature of the layer of thermoplastic KSv and the Vicatsoftening temperature of the layer of thermoplastic KSa is in each casehigher than the Vicat softening temperature of the layer ofthermoplastic KSw by at least 4 K.
 3. The sheetlike composite accordingto claim 1, wherein the melting temperature of the layer ofthermoplastic KSv and the melting temperature of the layer ofthermoplastic KSa is in each case higher than the melting temperature ofthe layer of thermoplastic KSw.
 4. The sheetlike composite according toclaim 3, wherein the melting temperature of the layer of thermoplasticKSv and the melting temperature of the layer of thermoplastic KSa is ineach case higher than the melting temperature of the layer ofthermoplastic KSw by at least 3 K.
 5. The sheetlike composite accordingto claim 1, wherein the modulus of the difference between the Vicatsoftening temperature of the layer of thermoplastic KSv and the Vicatsoftening temperature of the layer of thermoplastic KSa is in a range offrom 0 to 10 K.
 6. The sheetlike composite according to claim 1, whereinthe modulus of the difference between the melting temperature of thelayer of thermoplastic KSv and the melting temperature of the layer ofthermoplastic KSa is in a range of from 0 to 10 K.
 7. The sheetlikecomposite according to claim 1, wherein at least one of the layers ofthermoplastic KSu, KSv, KSa or KSw is a plastics mixture of at least twoplastics.
 8. The sheetlike composite according to claim 1, wherein atleast one of the layers of thermoplastic KSu, KSv, KSa or KSw is made ofa polyethylene or a polypropylene or a mixture of at least two of these.9. The sheetlike composite according to claim 7, wherein the plasticsmixture of at least one layer of thermoplastic contains as one of atleast two mixture components a polyolefin prepared by means of ametallocene.
 10. The sheetlike composite according to claim 1, whereinat least one of the layers of plastic KSu, KSv, KSa or KSw comprises atleast one polyolefin with a mass density in a range of from 0.925 g/cm³to 0.980 g/cm³ in a range of from 20 wt. % to 100 wt. %, in each casebased on the total weight of the layer of plastic.
 11. The sheetlikecomposite according to claim 1, wherein the barrier layer is chosen froma. a barrier layer of plastic, or b. a metal layer, or c. a metal oxidelayer or d. a combination of at least two of a. to c.
 12. The sheetlikecomposite according to claim 1, wherein the carrier layer has at leastone hole which is covered at least with the barrier layer and at leastwith one of the layers of thermoplastic KSa or KSw as hole-coveringlayers.
 13. A container surrounding an interior, comprising at least onesheetlike composite according to claim
 1. 14. A process for theproduction of a container surrounding an interior, comprising theprocess steps a. providing a sheetlike composite comprising a layerconfiguration with the following layers: o. optionally a layer ofthermoplastic KSu of a plastics composition KSum; i. a carrier layer;ii. a first layer of thermoplastic KSv of a plastics composition KSvm;iii. a barrier layer; iv. a second layer of thermoplastic KSa of aplastics composition KSam; and v. a further layer of thermoplastic KSwof a plastics composition KSwm; wherein the Vicat softening temperatureof the plastics composition KSvm and the Vicat softening temperature ofthe plastics composition KSam is in each case higher than the Vicatsoftening temperature of the plastics composition KSwm; b. folding thesheetlike composite to form a fold with at least two fold surfacesadjacent to one another, wherein layer v. faces the interior of thecontainer; c. joining at least a part region of the at least two foldsurfaces to form a container region.
 15. The process according to claim14, wherein at least one of the layers of thermoplastic KSu, KSv, KSa orKSw in step b. is heated above its melting temperature.
 16. The processaccording to claim 14, wherein at least one of the layers ofthermoplastic KSu, KSv, KSa or KSw in step b. has a temperature which isbelow its melting temperature.
 17. The process according to claim 14,wherein at least one of the layers of thermoplastic KSu, KSv, KSa or KSwhas a melting temperature below the melting temperature of the barrierlayer.
 18. The process according to claim 14, wherein at least one ofthe layers of thermoplastic KSu, KSv, KSa or KSw is produced byextrusion of at least one polymer P1 through a slot die to obtain anemerging surface, at least one polymer P2 which differs from polymer P1being provided on the flanks of the emerging surface of the at least onepolymer P1 emerging from the slot die.
 19. The process according toclaim 18, wherein the emerging surface is cooled to a temperature belowthe lowest melting temperature of the polymer P2, and at least theflanks of the emerging surface are then separated off from the emergingsurface.
 20. The process according to claim 14, wherein the foldsurfaces form an angle μ of less than 90°.
 21. The process according toclaim 14, wherein the joining according to step c. is carried out bysealing by means of at least one of the layers of thermoplastic KSu, KSaor KSw.
 22. The process according to claim 14, wherein at least one ofthe layers of thermoplastic KSu, KSa or KSw is heated above its meltingtemperature directly before step c.
 23. The process according to claim22, wherein the heating is carried out by irradiation, contact with ahot solid or hot gas, or a combination thereof.
 24. The processaccording to claim 22, wherein the heating is carried out by amechanical vibration.
 25. The process according claim 24, wherein theheating is carried out by ultrasound.
 26. The process according to claim14, wherein the container is filled with a foodstuff before step b. orafter step c.
 27. The process according to claim 14, wherein thesheetlike composite has at least one score and the fold is effectedalong the score.
 28. The process according to claim 27, wherein thescore demarcates the sheetlike composite into a part of large area and apart of small area compared with the part of large area.
 29. The processaccording to claim 14, wherein a further folding follows step c. as stepd., and wherein, in the further folding in step d., at least one of thelayers of thermoplastic KSu, KSv, KSa or KSw has a temperature which isbelow the melting temperature of this layer of plastic.
 30. A containerobtainable by a process according to claim
 14. 31. (canceled)